Hello, all!
This post talks about OSPF network types. Please see more details below.
BACKGROUND INFORMATION
By default, the physical interface type determines the network type.
The network type of an Ethernet interface is broadcast.
The network type of a serial interface running PPP or HDLC is P2P.
The network type of an ATM interface or a frame relay (FR) interface is NBMA.
The network types of the interfaces on both ends of a link must be the same; otherwise, the OSPF neighbor relationship cannot be established.
When the network type of one OSPF interface is broadcast and the network type of the other OSPF interface is P2P, the two interfaces can still set up the neighbor relationship but cannot learn the OSPF routing information each other.
When the network types of OSPF interfaces on both ends of a link are P2MP and P2P, the two OSPF interfaces can establish OSPF neighbor relationship but cannot learn routing information from each other. To enable the interfaces to learn routing information from each other, configure the same interval for sending Hello packets and same neighbor holdtime on the two OSPF interfaces.
This would be all on OSPF network types. Thanks for reading this post!